CVE-2016-4437 KEVPublic exploit Critical · 9.8 EPSS 93.0%

Apache Shiro Code Execution Vulnerability

Apache · Shiro

Summary

The flaw is in Apache Shiro, the Java security framework, and affects versions before 1.2.5 when the "remember me" feature is used without a configured cipher key. An attacker with network access can send a request containing an unspecified parameter to execute arbitrary code or bypass intended access restrictions, requiring no authentication or user interaction and only the vulnerable configuration.

Official description · NVD

Apache Shiro before 1.2.5, when a cipher key has not been configured for the "remember me" feature, allows remote attackers to execute arbitrary code or bypass intended access restrictions via an unspecified request parameter.

Breakdown

69.8 / 100

Exploited: Yes, in CISA KEV
Reports: 0
Tactics: 2/15

How an attack unfolds

Based on mappings. Select a step to see the evidence.

How attackers get in
- Break in through an internet-facing appT1190 · Exploit Public-Facing ApplicationSource dataMedium confidence149 general detection rules
What they do
- Run commands on the systemT1059 · Command and Scripting InterpreterSource dataMedium confidence95 general detection rules

First seen exploited 5 years after disclosure. Public exploit code (Metasploit) was available the same day.

DisclosedPublic exploit codeMetasploit7 Jun 2016day 0
First seen exploitedVulnCheck KEV evidenceAdded to CISA KEVEU database agrees3 Nov 2021+5 yrs

CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.

techniques

2 , grouped by in kill-chain order 2

Initial AccessTA0001

Exploit Public-Facing Application T1190 Medium

MITRE CTID mapping of the KEV entry · how it is exploited

CVE-2016-4437 is a code execution vulnerability in Apache Shiro that allows remote attackers to execute code or bypass access restrictions via an unspecified request parameter when a cipher key has not been configured for the "remember me" feature.

ExecutionTA0002

Command and Scripting Interpreter T1059 Medium

MITRE CTID mapping of the KEV entry · primary impact

Detection

0 rules for this CVE · 244 general rules for its techniques

Rules for this CVE

0 that reference CVE-2016-4437 directly.

CVE-specific rules are not available in this build. Search SigmaHQ ↗

General rules for this CVE’s techniques

These detect the technique in general, not this specific vulnerability.

Exploit Public-Facing ApplicationT1190149 general rules

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Confluence Exploitation CVE-2019-3398criticaltest
CVE-2010-5278 Exploitation Attemptcriticaltest
CVE-2020-0688 Exchange Exploitation via Web Logcriticaltest
CVE-2020-10148 SolarWinds Orion API Auth Bypasscriticaltest
CVE-2020-5902 F5 BIG-IP Exploitation Attemptcriticaltest

All 149 on SigmaHQ ↗

Command and Scripting InterpreterT105995 general rules

HackTool - Sliver C2 Implant Activity Patterncriticaltest
Lazarus Group Activitycriticaltest
REvil Kaseya Incident Malware Patternscriticaltest
Turla Group Lateral Movementcriticaltest
Windows Defender AMSI Trigger Detectedhighstable
Windows Defender Threat Detectedhighstable
Abusable DLL Potential Sideloading From Suspicious Locationhightest
Add Insecure Download Source To Wingethightest

All 95 on SigmaHQ ↗

Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.

Am I affected? What do I upgrade to?

From GitHub Security Advisories and OSV

1 package in 1 ecosystem. Main package: org.apache.shiro:shiro-core.

Mavenorg.apache.shiro:shiro-coreGHSA-p836-389h-j692

Upgrade to 1.8.0 or later

Fixes this CVE and 2 other known vulnerabilities in this package (CVE-2020-1957, CVE-2021-41303).

Set the version to 1.8.0 or later in your pom.xml or build.gradle.

First fixed in 1.2.5 for CVE-2016-4437.

Affected versions

If you run	Upgrade to
All versions before 1.2.5	1.8.0first fix for this CVE: 1.2.5

“Up to” means the second version is the fix and is not affected.

Check your lockfile against all CVEs

What security researchers reported

Not named in any threat report yet

Also mentioned in 50 community threat pulses (AlienVault OTX)

Weaker evidence

Pulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.

Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
Actively_Exploited_Kev | Oct 22, 202621 Oct 2026
44 more on OTX

References

8 links, grouped by NVD tag (7 duplicates merged)

Exploitation evidence

Exploited in the wild

Listed since 3 Nov 2021. Federal due date 3 May 2022. No recorded ransomware use.

Apply updates per vendor instructions.

ENISA

Marked exploited since 3 Nov 2021. EUVD-2022-4711

Apache Shiro 1.2.4 - Cookie RememberME Deserial RCE (Metasploit)EDB-48410 · remote · multiple · 2020-05-01 · verified

, 30 Oct 2026

93.0%Top 0.17%

Chance of exploitation in the next 30 days. of scored CVEs (riskier than 99.83%).

3.1

9.8Critical · 9.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Priority factorsFormula

In a KEV cataloglisted in CISA KEV and VulnCheck KEV 35.0/35

Recent KEV listingadded 1823 days ago 0.0/10

Known ransomware usenot known 0.0/10

EPSS percentilepercentile 0.9983 20.0/20

Threat reports0 reports 0.0/10

Public exploit code1 NVD reference tagged Exploit; 1 Exploit-DB entry; 1 NVD exploit link; 6 PoC-in-GitHub repos; 1 Metasploit module; 1 nuclei template 5.0/5

Mentioned in OTX pulses50 pulses 3.0/3

CVSS base scorebase score 9.8 6.9/7

End-of-life productsupported or unknown 0.0

Total69.8

Record

Published: 7 Jun 2016
Modified: 17 Jun 2026
: CWE-321 Use of Hard-coded Cryptographic KeyCWE-284 Improper Access Control
Elsewhere: NVD CVE.org KEV JSON

How an attack unfolds

1How attackers get in

2What they do

Exploitation timelineExploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.

ATT&CKMITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques

Initial AccessTA0001

ExecutionTA0002

Detection

Rules for this CVE

General rules for this CVE’s techniques

Am I affected? What do I upgrade to?

Affected versions

What security researchers reported

Also mentioned in 50 community threat pulses (AlienVault OTX)

References

US Government Resource 1

Third Party Advisory 6

Mailing List 1

How attackers get in

What they do

techniques